The present invention relates to a steel laminate gasket for an internal combustion engine having two separate beads for providing desired sealing pressure around a hole to be sealed.
The steel laminate gasket of the invention can be used widely, such as a regular gasket situated between two engine blocks, cylinder head gasket and manifold gasket. Further, in the gasket of the present invention, cylinder holes Hc, water holes Hw, oil holes Ho, bolt holes Hb and the like, as shown in FIG. 1 can be easily and securely sealed.
In the steel laminate gasket, one of the very important things when the steel laminate gasket is designed is how portions around holes of the engine are securely sealed. If the portions around the holes of the engine are not properly sealed, the engine does not operate as intended. In this respect, there have been proposed many methods.
One of conventional methods for sealing around holes, such as a cylinder hole Hc, is shown in FIG. 2, wherein a gasket 20 comprises an upper plate 21, a lower plate 24, a middle plate 22, and a middle plate 23 having a bead 23a around a cylinder hole Hc to be sealed. The lower plate 24 is provided with a curved portion 24a located around the hole Hc, and a flange portion 24b situated above the upper plate 21. In the gasket 20, the curved portion 24a together with the bead 23a seals around the hole Hc.
When the gasket 20 is assembled, after the plates are stacked together, the curved portion 24a must be bent. In this respect, in case a hole to be sealed is small, configuration of the hole is complicated or metal quality relative to bending is not good, a curved portion may crack. If a crack is formed on the bending portion, sealing ability of the gasket decreases, and therefore the gasket can not be used any more. Therefore, the bending portion can not be employed for sealing all kinds of holes.
When the curved or bending portion is not used, a gasket 25 as shown in FIG. 3 may be used. The gasket 25 comprises an upper plate 26, a lower plate 28 and a middle plate 27 having a bead 27a around a hole Hc. In this gasket 25, the bead 27a only provides a sealing pressure around the hole Hc. Therefore, fluid passing through the hole Hc may possibly permeate through the plates. The sealing ability of the gasket 25 is not good.
In view of the prior art as stated above, a steel laminate gasket with high sealing ability had been proposed and filed on June 26, 1987, which was patented on July 26, 1988 as U.S. Pat. No. 4,759,585. The gasket is provided with at least two plates with beads respectively, wherein when the gasket is tightened, the beads diagonally push with each other to provide high sealing pressure around a hole.
The gasket of the present invention does not basically provide so high sealing pressure as in the gasket disclosed in U.S. Pat. No. 4,759,585, but the gasket of the invention can provide sufficient sealing pressure and securely seal around a hole to be sealed.
Accordingly, one object of the present invention is to provide a steel laminate gasket, which can provide moderate sealing pressure around a hole and seal securely around the hole.
Another object of the present invention is to provide a steel laminate gasket as stated above, wherein sealing pressure applied around a hole to be sealed can be controlled as desired.
A further object of the present invention is to provide a steel laminate gasket as stated above, which can provide high sealing pressure if desired.
A still further object of the present invention is to provide a steel laminate gasket as stated above, which can be easily and economically manufactured.
Further objects and advantages of the invention will be apparent from the following description of the invention.